Gas turbine rotor blade and gas turbine

Abstract

A platform of a gas turbine rotor blade according to one embodiment includes a groove portion recessed from an end surface on a trailing edge side toward a leading edge side. A bottom portion of the groove portion overlaps at least a blade-shaped portion when viewed from a radial direction. When a pressure-side end portion of the platform with respect to the bottom portion is defined as a first point, a tangent line that is a tangent line with respect to the bottom portion, extending along a plane intersecting the radial direction at the first point is defined as a first tangent line, when an intersection between a line segment connecting the bottom portion and an end portion on the trailing edge side of a serpentine cooling flow path provided inside the blade-shaped portion when viewed from the radial direction and an end portion on the trailing edge side of the blade-shaped portion is defined as a second point, a tangent line that is a tangent line with respect to the bottom portion, extending along the plane at the second point is defined as a second tangent line, and when an intersection between the first tangent line and the second tangent line when viewed from the radial direction is defined as a third point. As viewed from the radial direction, the third point exists on a side opposite to the end portion on the trailing edge side of the blade-shaped portion across a straight line connecting the first point and the second point.

The invention claimed is: 
     
       1. A gas turbine rotor blade comprising:
 a base end portion fixed to a rotor; 
 a blade-shaped portion extending in a radial direction of the rotor and having a pressure-side blade surface and a suction-side blade surface, the blade surfaces forming a blade shape between a leading edge and a trailing edge of the blade-shaped portion; and 
 a platform provided between the base end portion and the blade-shaped portion, wherein 
 the platform includes a groove portion recessed from an end surface on the trailing edge side toward the leading edge side and extending in a circumferential direction of the rotor, 
 a bottom portion of the groove portion overlaps at least the blade-shaped portion when viewed from the radial direction, 
 when a pressure-side end portion of the platform with respect to the bottom portion is defined as a first point, a tangent line that is a tangent line of the bottom portion at the first point and extends along a plane intersecting the radial direction is defined as a first tangent line, 
 when an intersection between a line segment connecting the bottom portion and an end portion on the trailing edge side of a serpentine cooling flow path provided inside the blade-shaped portion when viewed from the radial direction and an end portion on the trailing edge side of the blade-shaped portion is defined as a second point, a tangent line that is a tangent line of the bottom portion at the second point and extends along the plane is defined as a second tangent line, 
 when an intersection between the first tangent line and the second tangent line when viewed from the radial direction is defined as a third point, when viewed from the radial direction, the third point exists on a side opposite to the end portion on the trailing edge side of the blade-shaped portion across a straight line connecting the first point and the second point. 
 
     
     
       2. The gas turbine rotor blade according to  claim 1 , wherein when viewed from the radial direction, the bottom portion intersects the suction-side blade surface and the pressure-side blade surface outside of a first virtual circle centered on the end portion on the trailing edge side of the blade-shaped portion and passing over the line segment. 
     
     
       3. The gas turbine rotor blade according to  claim 1 , wherein when viewed from the radial direction, the bottom portion intersects the suction-side blade surface outside of a second virtual circle centered on an end portion on the trailing edge side of the serpentine cooling flow path and passing over the line segment. 
     
     
       4. The gas turbine rotor blade according to  claim 1 , wherein a depth of the groove portion recessed from the end surface on the trailing edge side toward the leading edge side is deeper on the pressure-side than on the suction-side. 
     
     
       5. The gas turbine rotor blade according to  claim 1 , wherein a depth of the groove portion recessed from the end surface on the trailing edge side toward the leading edge side is constant at a position away from the end portion on the trailing edge side of the blade-shaped portion relative to an intersection position between the bottom portion and the suction-side blade surface when viewed from the radial direction. 
     
     
       6. The gas turbine rotor blade according to  claim 1 , wherein a depth of the groove portion recessed from the end surface on the trailing edge side toward the leading edge side is at least partially constant in a region between the first point and an intersection position between the bottom portion and the pressure-side blade surface when viewed from the radial direction, the region including the first point. 
     
     
       7. The gas turbine rotor blade according to  claim 1 , wherein
 the platform includes a seal pin groove in which a seal pin for sealing a gap between the platform and a platform of another gas turbine rotor blade adjacent to each other in the circumferential direction is arranged, 
 the seal pin groove is formed on an end surface on a suction-side of the platform, and 
 an end surface on a pressure-side of the platform includes a plane that can come into contact with a seal pin arranged at a position opposing the end surface. 
 
     
     
       8. A gas turbine comprising:
 the rotor; and 
 the gas turbine rotor blade according to  claim 1  fixed to the rotor at the base end portion.